docs: def get_pac(self):
          """
          Search for, download, and parse PAC file if it hasn't already been done.
          This method is called upon the first use of :meth:`request`,
          but can also be called manually beforehand if desired.
          Subsequent calls to this method will only return the obtained PAC file, if any.
  
          :returns: The obtained PAC file, if any.
          :rtype: PACFile|None
          :raises MalformedPacError: If something that claims to be a PAC file was downloaded but could not be parsed.
          """
          if self._tried_get_pac:
              return self._proxy_resolver.pac if self._proxy_resolver else None
  
          if not self.pac_enabled:
              return
  
          pac = get_pac()
          self._tried_get_pac = True
          if pac:
              self._proxy_resolver = self._get_proxy_resolver(pac)
          return pac